This was just being talked about this morning on this guys morning talk show. Give this link a look...
http://www.mastalk.com/mastalk/readOfTheDay.jspx
Red is bad.
As far as noise goes...It's Philly, there will always be noise. You would probably want to hit the burbs for some quiet, and those maps linked above cover them as well. As far as a 1bdrm goes in Philly, chances are you're not going to find something safe and quiet for $650. You will probably spend anywheres from $800 to $1200 a month for a one bedroom in a safe part of the city. You may have to go to the burbs to find something cheaper...think: Manyunk and Roxborough in PA, Collingswood and surrounding areas in NJ. Otherwise, hit Craigslist and try and find yourself someone who is looking for a roommate. THEN you may be able to rent in that price range, as 2 bdrms are normally $1100-$2000 a month, again, depending on where it is.
Northern Liberties, Philly (see 2nd & Poplar as a center): Not too quiet as 2nd Street is almost a dragstrip. Plenty of good bars to hit, lots of nice people, very artsy fartsy...mostly musically...but there is still crime in the area. Nothing ridiculous like drive-bys and murders, though car break-ins are not uncommon, the bank on 2nd has been robbed multiple times (by the same guy who has been caught) and there has been a few sexual assaults (I believe they caught him as well).
Center City: Very pricey, but due to the exposure, it's a little more safe than surrounding areas. Biggest problem is mostly the vagrants who range from just pests to the type you should carry mace just in case for.
South Philly: Is hit or miss. That's something you need to see for yourself. You could be on one corner and it's a great, family kind of 'hood where everyone knows everyone but you could cross the street and get yourself in some real trouble.
Fairmount: Closer to Spring Garden Street seems to be safer in my honest opinion. Girard Avenue, from the River to the Zoo seems to be a pretty hairy place to be regardless of the block. It's probably a safe bet to stay away from Girard unless you find a safer spot in the Northeast. At that point though, you're going to be a good 30 mintues outside of the city and the crime ridden areas will be very hit or miss.
The Art Museum Area: Can be very nice, and somewhat safe. Again, keep away from Girard.
University City: Is the area consisting of UPenn and Drexel University. It's obviously a college crowd, however there's been a recent BIG surge in violence surround University City High School.
South Street: Very loud, somewhat safe but is typically crawling with the freaky freaks. Close to the River though.
Old City: Will most likely be very expensive and out of your price range (for a one bedroom), but just in case--it can be very loud, and even though there are a lot of nice bars, restaraunts and lounges, they typically explode with tight black t-shirt, Axe Body Spray wearing spikey hair guys or girls who...eh...ho's.
12th & Spruce and surrounding area: The Gayborhood. Honestly, it's one of the nicest, friendliest and I think safest areas in the city. It is getting to be very expensive though due to that fact.
West Philly: Just stay away.
South Jersey: Stay out of Camden. It has the potential to be a great part of NJ one day, but today ain't it. The Aquarium, the E-Center and the Rivershark's Stadium are all very nice places with incredible views of Center City, especially during the sunset, but you'd better be getting out of there about that time, or your chances of something bad happening increase dramatically.
Cherry Hill: Isn't too much of an apartment community, but like I said, if you check out Craigslist, you're bound to find something. Stay close to areas near the PATCO high speed line A) for convenience and B) now that I think of it, the communities along that line are relatively safe, and definitely quieter than Philly. Think, Cherry Hill, Collingswood, definitely Haddonfield, etc. It's tough to get to the bars though, as they're kind of spread out and the NJ cops can be real hard-asses, so driving (even though it should be already) is out of the question unless you're the DD.
You could also follow the Riverline, a new line from NJ Transit. It runs 24 hours from Camden to Trenton, and is a great way to commute. It's been a big deal for manypeople along the River in NJ. However, it's not the same as PATCO as far as the communities go. Pennsauken, Willingboro, Beverly, Bordentown can all be hairy in their own South Jersey white bread kind of way.
The other towns I can think of off the top of my head that are nice, though not so much rental communities are: Haddon Heights, Moorestown, Marlton, Medford, Mount Laurel, Collingswood, parts of Merchanville, Haddonfield and Voorhees.
Wow....this is kind of long. Sorry about that. Email me if you have any more questions. Be safe driving.